Friday, August 16, 2013

SIGCOMM13: SplitX: High-Performance Private Analytics

Presented by: Ruichuan Chen

Authors: Ruichuan Chen, Istemi Ekin Akkus, Paul Francis

SplitX is a high-performance private analytics system resistant to answer pollution. It is designed under the assumption that analysts and clients are potentially malicious while servers are honest. 

The key factors differentiating SplitX from other analytics systems are XOR encryption and query buckets. SplitX achieves high performance in terms of bandwidth and computation by substituting cryptographic encryption with XOR operation. In order to limit answer pollution, clients are restricted to answer queries in binary format.

In the SplitX system, clients subscribe to the queries published by the analysts. Clients split their answer and send them to mixes, which add differentially private noise to the messages. Aggregators generate query results by combining the outputs of the mixes. Double-splitting is used at the mixes to guarantee privacy.

Q: What are the long-term incentives in using this system?
A: SplitX is highly relevant in the current scenario where users are increasingly concerned about privacy.

Q: SplitX uses splitting at several stages. What is the time required per splitting?
A: Splitting involves XOR operation only. Since XOR is extremely efficient, the time required for splitting is negligible.